Jenson Button believes Nico Rosberg will be in for a surprise when he goes head-to-head with Lewis Hamilton at Mercedes next year.

Button has been Hamilton's team-mate for the past three seasons, but Hamilton will move from McLaren to Mercedes at the end of this year. Rosberg has an impressive record against his team-mates in F1, beating his opposite number on every occasion apart from his debut season alongside Mark Webber at Williams in 2006, but Button thinks Hamilton's raw pace will still come as a shock to Rosberg.

"I think he'll probably get a bit of a surprise at his speed," he said. "I know he's been his team-mate in the past but I think he'll be surprised at how Lewis can get performance out of a bad car. I think that will be the biggest thing."

In terms of his personal relationship with Hamilton, Button admitted that Rosberg, who was Hamilton's team-mate in go-karts, knows him better.

"I think he knows him pretty well," he added. "I think Nico knows Lewis better than I do. They've worked together before and I'm sure he knows what to expect [from their working relationship]."